1. Field of the Invention
The present invention relates to a developing apparatus and a developing method and, more particularly, to an apparatus and a method for developing a thick film photoresist of not less than 10 μm, for example.
2. Description of the Background Art
There has hitherto been known a method by which a photoresist is applied to a substrate to be treated, such as a semiconductor wafer, a circuit pattern is transferred to the photoresist by using photolithography technology, and a developing solution is supplied to a surface on which an undeveloped image pattern is formed, whereby a developed image pattern is formed on the front surface of the substrate to be treated by developing the applied resist film to form a circuit.
Developing equipment includes a developing apparatus in which a substrate to be treated is immersed in a developing solution, a developing apparatus in which a developing solution is caused to flow as a shower on the front surface of a substrate to be treated, and a paddle type developing apparatus in which a developing solution is applied over a photoresist on the front surface of a substrate to be treated and the developing solution is thrown off by rotating the substrate to be treated after a lapse of a predetermined time.
Prior arts of paddle type developing apparatus in which a developing solution is sprayed in mist form are exemplified below.
There is known a developing method by which after the completion of the paddle development, a developing solution and nitrogen gas are mixed at a ratio of 1:1 and the mixture is sprayed in mist form during the rotation of a wafer so that no scum of a photoresist film remains on the wafer. (Patent Document 1)
There is also known a paddle developing method by which a developing solution and nitrogen (air) are supplied to a nozzle via separate pipes and the developing solution is sprayed in spray form, thus permitting high accuracy development treatment. (Patent Document 2)
There is further known a paddle developing method by which a developing solution supply pipe and a gas supply pipe are caused to face an umbrella-like concave portion formed at the bottom end of a nozzle and a developing solution is supplied to a substrate in the form of a high velocity mist. (Patent Document 3).
On the other hand, in the prior art of paddle type developing apparatus, there is known a means of preventing a developing solution from flowing behind the rear surface of a wafer after the development performed by dropping the developing solution. (Patent Document 4) (Patent Document 5)
[Patent Document 1] Japanese Patent Laid-Open No. 6-45244
[Patent Document 2] Japanese Patent Laid-Open No. 7-326559
[Patent Document 3] Japanese Patent Laid-Open No. 2002-208579
[Patent Document 4] Japanese Patent Laid-Open No. 56-160035
[Patent Document 5] Japanese Patent Laid-Open No. 60-142517
Spraying a developing solution in mist form in performing paddle type development can reduce the consumption of a developing solution and is desirable from the standpoint of uniform treatment.
In the cited Document 1 to Document 4, however, in all of the prior arts, a developing solution is used at room temperature and, therefore, the development time is long, posing the problem that the development treatment rate decreases.
Furthermore, although it is possible to maintain the temperature of a developing solution at a predetermined level until the moment the developing solution is delivered, the temperature and concentration of the solution change due to vaporization after the delivery, with the result that it is difficult to maintain a prescribed performance of the developing solution, and posing the problem that an unevenness of development tends to occur.
In addition, a developing solution flows behind the rear surface of a wafer, posing the problem that a spinner shaft becomes dirty easily.
Incidentally, in Patent Document 4, the liquid is prevented from flowing behind the rear surface of a wafer by forming a fan portion on a wafer chuck. However, the fan portion extends in a radial pattern as part of the wafer chuck and the total surface area which cuts the air during rotation is wide. Therefore, considerable air resistance occurs during the rotation of this wafer chuck and a load to a rotary shaft increases, with the result that the start-up of rotation requires time, leading to a decrease in production efficiency.
On the other hand, in Patent Document 4, there is also an example in which a wafer chuck portion and a blowing member on which a fan is mounted are separated from each other so that an increase in load to a rotary shaft is prevented. In the case of poor gap adjustment or in the case of a large face runout of a wafer, a fan and the wafer come into contact with each other and the wafer might be damaged. Conversely, when the gap is too large, the fan effect decreases, posing the problem that adjustment is difficult.
In FIG. 3 of Patent Document 5, a fan is attached to a spindle on the side of the rear surface and streams of air current are formed from the center of the spindle to the circumference thereof by use of the fan. However, it is necessary to provide two members, i.e., the fan which forms the streams of air current from the center of the spindle to the circumference thereof and an inlet port which sucks in the streams of air current, and the mechanism becomes complicated, posing the problem that the cost increases.
The present invention was made in view of the above-described problems and has as its object the provision of a developing apparatus and a developing method which shorten the development time of a resist (in particular, with a thick film of not less than 10 μm) and permit uniform development.